Systems and methods for pipeline rehabilitation

ABSTRACT

The present disclosure is directed to methods and systems for pipeline rehabilitation. The methods and systems disclosed herein permit the rehabilitation of long lengths of previously installed pipe and minimize the need for creating multiple access points to the pipeline. The disclosed systems and methods are particularly suited for rehabilitating buried and undersea pipelines or pipelines installed in areas of restricted access.

RELATED APPLICATION INFORMATION

This application claims priority to provisional U.S. Patent Application60/368,503 filed Mar. 29, 2002, which is hereby incorporated byreference in its entirety.

BACKGROUND

Pipelines for transporting fluids such as oil and natural gas maydeteriorate over time potentially resulting in leakage of fluid from thepipeline. In the case of metal piping, for example, corrosion may be asignificant cause of pipe deterioration. Repair of previously installedpiping may be difficult and expensive, particularly in the case ofburied or submerged pipelines where access to the pipeline isrestricted. Successful repair of buried pipeline may require multipleaccess points, resulting in significant disturbances of the areasproximate the access points and potentially adverse environmental impactat each area. For these reasons, there is a need for improved systemsand methods for rehabilitating pipelines.

SUMMARY

The present disclosure is directed to methods and systems for pipelinerehabilitation. The methods and systems disclosed herein permit therehabilitation of long lengths of previously installed pipe and minimizethe need for creating multiple access points to the pipeline. Thedisclosed systems and methods are particularly suited for rehabilitatingburied and undersea pipelines or pipelines installed in areas ofrestricted access.

In one exemplary embodiment, a method of rehabilitating a pipelinecomprising a first pipe comprises inserting a second pipe into the firstpipe and pushing and pulling a length of the second pipe through thefirst pipe. The first pipe may act as a conduit for installing thesecond pipe and the second pipe, once installed, may be utilized totransport fluids in place of the first pipe, thereby rehabilitating thepipeline. The exemplary method may also include providing a first accesspoint in the first pipe for insertion of the second pipe and providing asecond access point in the first pipe that is spaced apart from thefirst access point and permits the second pipe to pulled through thefirst pipe. Pushing and pulling the second pipe through the first pipemay better control the position of the second pipe within the first pipeand may reduce tensile strain on the second pipe. The second pipe may besimultaneously pushed and pulled through the first pipe and/oralternatively pushed and pulled through the first pipe.

The exemplary method may also include flooding the first pipe with afluid, such as water, prior to pushing and pulling the second pipethrough the first pipe. The buoyancy of the second pipe in the floodedfirst pipe may be controlled to facilitate pushing and pulling of thesecond pipe through the first pipe. For example, in certain embodiments,the exemplary method may include adjusting the buoyancy of the secondpipe to approximately neutral buoyancy or to minimal negative buoyancy,for example, to a weight of approximately 0.10 lbs. per ft. in water.The buoyancy of the second pipe may be adjusted by coupling a buoyancycontrol layer to the second pipe. The buoyancy control layer may be alayer of material(s) having a density selected to adjust the overalldensity of the second pipe to provide a desired buoyancy to the secondpipe. The buoyancy control layer may be coupled to the pipe by extrudinga material having the desired density onto the exterior of the secondpipe, by wrapping a material having the desired density onto theexterior of the pipe, or by other methods of coupling a layer ofmaterial to the exterior or other portion of a pipe. The buoyancycontrol layer may be coupled to the second pipe during fabrication ofthe second pipe or in a post-fabrication process. The material of thebuoyancy control layer may be selected to provide increased wearresistance to the second pipe and to reduce the coefficient of frictionof the exterior of the second pipe.

In other exemplary embodiments, the method may include flooding thefirst pipe with a fluid having a density selected to provide a desiredbuoyancy to the second pipe. For example, a dense fluid, such as brineor water-based drilling mud, may be delivered to the first pipe to floodthe first pipe such that the second pipe has neutral or minimal negativebuoyancy within the dense fluid. In an exemplary embodiment, thebuoyancy of the second pipe may be controlled by both flooding the firstpipe with a fluid and coupling a buoyancy control layer to the secondpipe.

The exemplary method may include introducing friction reducing fluids tothe interior of the first pipe to reduce friction forces between thefirst pipe and the second pipe as the second pipe is pushed/pulledthrough the first pipe. The friction reducers may be fluids such as oilsor other lubricants that are pumped into the first pipe before or duringthe pushing/pulling operation.

In other exemplary methods, sensors and/or transmitters may be affixedto or integral with the second pipe, affixed to the first device,affixed to the second device, or may be affixed to or integral with thefirst pipe to measure pipeline rehabilitation process parameters, suchas, for example, the axial and radial location of the second piperelative to the first pipe, fluid leakage within the first or secondpipe, and strain on the second pipe. Exemplary sensors include, forexample, load cells, displacement transducers, accelerometers, acoustictransmitters, clearance gauges, and imaging devices.

In one exemplary embodiment, a system for rehabilitating a pipelinecomprising a first pipe comprises a first device adapted to be coupledto a first portion of a second pipe, the first device being configuredto push a length of the second pipe into a first access point of thefirst pipe, and a second device adapted to be coupled to a secondportion of the second pipe, the second device being configured to pullthe second pipe through a second access point in the first pipe, thesecond access point being spaced apart a distance from the first accesspoint. The first device may be an injector, a hydraulically or otherwiseoperated reel upon which the second pipe is mounted, and/or otherdevices suitable for deploying long lengths of pipe. The second devicemay be a capstan, a winch, a tractor, propulsion jets, and/or otherdevices suitable for pulling long lengths of pipe, cables, ropes, orcords. The first device and the second device may be operatedsimultaneously to affect the simultaneous pushing and pulling of thefirst pipe through the second pipe.

In one exemplary embodiment, a method of adjusting the buoyancycharacteristics of a pipe includes providing a pipe and adding a layerof material having a density selected to modify the overall density ofthe pipe. The additional layer may be extruded onto an exterior layer ofthe pipe; deposited, for example, wrapped, wound or sprayed, onto theexterior of the pipe; or otherwise coupled to the pipe. In oneembodiment, the additional layer may be a layer of thermoplastic foamextruded onto an exterior layer of the first pipe.

BRIEF DESCRIPTIONS OF THE DRAWINGS

These and other features and advantages of the systems and methodsdisclosed herein will be more fully understood by reference to thefollowing detailed description in conjunction with the attached drawingsin which like reference numerals refer to like elements throughout thedifferent views. The drawings illustrate principals of systems andmethods disclosed herein and, although not to scale, show relativedimensions.

FIG. 1 is a schematic view of a system for pipeline rehabilitation;

FIG. 2 is a side elevational view of a rehabilitated pipe having asecond pipe that includes a buoyancy layer;

FIG. 3 is a side elevational view of a rehabilitated pipe having abuoyancy controlling fluid controlling the buoyancy of a second pipe;and

FIG. 4 is a side elevational view in cross-section of a composite pipehaving a buoyancy control layer.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 1 illustrates an exemplary embodiment of a system 10 forrehabilitating a pipeline comprising a first pipe. The system 10comprises a first device 12 that is configured to push a length of asecond pipe 14 into a first access point 16 of the first pipe 18. Thesystem 10 further includes a second device 20 that is configured to pullthe second pipe 14 through a second access point 22 in the first pipe18. The system 10 operates to push and/or pull the second pipe 14through the first pipe 18. During operation, the first pipe 18 acts as aconduit for installing the second pipe 14. The second pipe 14, onceinstalled, may be utilized to transport fluids in place of the firstpipe 18, thereby rehabilitating the pipeline. The exemplary system 10permits the rehabilitation of the pipeline with a minimum number ofaccess points in the first pipe 18 comprising the pipeline. In theillustrated embodiment, for example, two access points 16, 22 areprovided in the first pipe 18.

The systems and methods for pipeline rehabilitation described herein,including the exemplary system 10, are particularly suited forrehabilitation of buried and undersea pipeline and other pipelines inwhich access to the pipeline may be restricted. In the illustratedembodiment, for example, the first pipe 18 comprising the pipeline isburied underground. One skilled in the art will appreciate that thesystems and methods described herein are not limited to buried orundersea pipelines but instead may be utilized to effect rehabilitationof any installed pipelines. Likewise, the orientation of the firstdevice 12 and the orientation of the second device 20 relative to thefirst pipe 18, and in the exemplary embodiment, relative to the ground,may be varied. For example, the first device 12 and the second device 20may be oriented to introduce the second pipe 14 at an angle proximate to90° relative the first pipe 18 as illustrated in FIG. 1, at angleproximate to 0° (i.e., parallel) to the first pipe 18, or at any otherangle.

Continuing to refer to FIG. 1, the first device 12 of the exemplarysystem 10 may comprise an injector 23 that operates to engage theexterior surface of the second pipe 14 and push the second pipe 14 intothe first access point 16 of the first pipe 18. The second pipe 14 maybe fed to the injector 23 by a hydraulically or otherwise operated reel24 onto which the second pipe 14 may be spooled. The reel 24 maycooperate with the injector 23 to push the second pipe 14 into the firstpipe 18. Alternatively, the injector 23 or the reel 24 may independentlyoperate to push the second pipe 14 into the first pipe 18. One skilledin the art will appreciate that the first device 12 is not limited tothe injector 23 and or the reel 24 illustrated in FIG. 1. Any devicesuitable for displacing pipe, rope, cords, or other lengthy products maybe utilized as the first device. A push control station 25 coupled tothe injector 23 and/or the reel 24 may be provided to control theoperation of the injector and the reel.

In the exemplary system 10, the second device 20 may be a hydraulicallyor otherwise operated capstan 26 that is connected to an end of thesecond pipe 14 by a rope 28. The capstan 26 operates to pull the rope28, and, thus, the second pipe 14, through the first pipe 18. The rope28 is preferably a lightweight, high tensile strength rope or cord.Suitable ropes and/or cords include for example wires, wirelines,chains, fiber ropes, wire ropes, tubing and the like. Ropes may be, forexample, constructed from kevlar, polypropylene, metals, or otherlightweight, high strength materials. In one exemplary embodiment, therope 28 has a tensile strength of at least 40,000 lbs. An end connector31 may be provided at the leading end of the second pipe 14 to permitconnection of the pipe to the rope 28. The rope 28 may be wound onto ahydraulically or otherwise operated reel 30. The reel 30 may operate toassist the capstan 26 in pulling the second pipe 14 through the firstpipe 18. The capstan 26 and the reel 30 may independently operate toaffect pulling of the rope 26 and the second pipe 14. One skilled in theart will appreciate that other devices suitable for pulling pipe, rope,cords, wires, etc, including, for example an injector or a winch, may beutilized in conjunction with or in place of the capstan 26 and/or thereel 30. A pull control station 32 coupled to the capstan 26 and/or thereel 30 may be provided to control the operation of the capstan and thereel. The pull control station 32 may also be in wireless or wiredcommunication with the push control station 25 to coordinate theoperation of the first device 12 and the second device 20.Alternatively, a single control station may be provided to controloperation of the first device 12 and the second device 20.

In certain embodiments, the buoyancy of the rope 28 may be adjusted toprovide the rope 28 with neutral or minimal negative buoyancy within afluid provided in the first pipe 18. Neutral or minimal negativebuoyancy may provide extended reach pulling capabilities for the rope28. Coupling a buoyant material to the rope 28 or constructing the rope28 from a material having the desired buoyancy characteristics mayadjust the buoyancy of the rope 28. For example, a jacket of low-densityfoam may be extruded onto or otherwise coupled to the rope 28.

The first device 12 and the second device 20 may be operatedsimultaneously to affect simultaneous pushing and pulling of the secondpipe 14 through the first pipe 18. Alternatively, the first device 12and the second device 20 may be operated separately and independently tointroduce the second pipe 14 into the first pipe 18.

Depending on the length of the pipeline being rehabilitated, it may benecessary to connect two or more lengths of pipe for insertion into thepipeline. Thus, in certain embodiments, the second pipe 14 may comprisetwo or more lengths of pipe connected by one or more pipe-to-pipeconnectors 34. Each pipe-to-pipe connector 34 may be fitted with one ormore devices, such as a centralizer, for positioning the second pipe 14radially within the first pipe 18 to minimize instances of the secondpipe 14 becoming snagged on obstructions, such as welds or pipe joints,in the first pipe 18. In addition, each pipe-to-pipe connector may befitted with one or more mechanical rollers or other similar device andmay be covered with a material having a low coefficient of friction tofacilitate transport of the connector within the first pipe 18.

In certain embodiments, the second pipe 14 may be marked atpredetermined spaced-apart distances to permit measurement of the lengthof the second pipe 14 installed into the first pipe. In the event thesecond pipe 14 becomes obstructed, the markings may be useful inidentifying the location of an obstruction in the first pipe 18. Inaddition, a magnetic device or an RF transmitter or other type oftransmitter may be provided at the leading end or other locations of thesecond pipe 14 to monitor the advancement of the second pipe 14 throughthe first pipe 18. In certain embodiments, a relief pin or other similarload relieving device may be coupled to the rope 28 and/or capstan 26proximate the second device 20. The relief pin may be designed to yieldat an axial load less than the maximum tensile load allowable for thesecond pipe 14.

The second pipe 14 preferably has a high tensile strength to weightratio to facilitate displacement through the first pipe 18, inparticular to facilitate the pulling of the second pipe 14 through thefirst pipe 18. The desired tensile strength of the second pipe 14 willvary depending on the length and weight of pipe being deployed. Incertain exemplary embodiments, the tensile strength of the second pipe14 may be at least 10,000 lbs. In an embodiment, the tensile strength ofthe second pipe 14 may have sufficient tensile strength to facilitatedisplacement through the first pipe 18. The second pipe 14 may beconstructed of any material suitable for transporting fluids and havingthe requisite tensile strength for displacement through the first pipe18. Other characteristics of the second pipe may include high strengthand stiffness in the axial, hoop, and radial direction to carry loadsthat may be imposed on the second pipe in service, in place of the firstpipe, preferably without receiving support from the first pipe. Suitablepipes include metal pipes, for example, steel pipes, pipes constructedfrom plastics, for example, thermoplastic and thermoset materials, andcomposite pipes such as fiber reinforced plastic pipes andmetal/composite pipes, and composite hoses constructed from reinforceselastomers and plastics. In certain exemplary embodiments, the secondpipe 14 is a composite pipe constructed of a fluid impervious innerliner and a composite layer as described in detail below, such as,spoolable composite line pipe available from Fiberspar Corporation ofWest Wareham, Mass.

In an exemplary method of rehabilitating a pipeline, the second pipe 14may be inserted into the first pipe 18 and the second pipe 14 may bepushed and/or pulled through the first pipe 18. Initially, the firstaccess point 16 and the second access point 22 may be formed in thepipeline, i.e., the first pipe 18. A pig, plug, or other suitable devicemay be used to transport the rope 28 or a messenger line between thefirst access point 22 and the second access point 16. The rope 28 maythen be connected to an end of the second pipe 14. The second pipe 14may then be pushed by the first device 12 and the pulled by the seconddevice 10, through rope 28, to displace the second pipe 14 through thefirst pipe 18.

The exemplary method may also include flooding the first pipe 18 with afluid, such as water, prior to and/or during displacement of the secondpipe 14 through the first pipe 18. The buoyancy of the second pipe 14within the fluid of the flooded first pipe 18 may be controlled tofacilitate displacement of the second pipe 14 through the first pipe 18.In an embodiment, a rope 28 may then be connected to an end of thesecond pipe 14 to facilitate displacement through the flooded first pipe18. As described in detail below, a buoyancy control layer may beprovided to the second pipe 14 to adjust the buoyancy of the second pipe14. FIG. 2 illustrates a second pipe 14 through a first pipe 18, wherethe second pipe includes a composite tube 50 having an interior liner52, a composite layer 54, and buoyancy layer 56. In this illustration,the first pipe 18 is flooded with a fluid 19.

Alternatively, the first pipe may be flooded with a fluid having adensity selected to provide a desired buoyancy to the second pipe 14 tothereby control the buoyancy of the second pipe 14. For example, a densefluid, such as brine or water-based drilling mud, may be delivered tothe first pipe 18 to flood the first pipe 18 such that the second pipe14 has neutral buoyancy within the dense fluid. FIG. 3 illustrates asecond pipe 14 having an interior liner 52 and a composite layer 54through a first pipe 18, where the first pipe is flooded with a fluid 19selected to control the buoyancy of the second pipe 14.

The exemplary method may include introducing friction-reducing fluids tothe interior of the first pipe 18 to reduce friction forces between thefirst pipe 18 and the second pipe 14 as the second pipe is displacedthrough the first pipe 18. The friction reducers may be fluids such asoils or other lubricants that are pumped into the first pipe 18 beforeor during the pushing/pulling operation.

Another exemplary method may include additional fluids introduced to theinterior of the first pipe 18. Examples of additional fluids may includeviscofiers, lubricants, stabilizers, anti-foaming agents, and the like.

In certain embodiments, the second pipe 14 may be filled with a fluid,such as water, to allow hydro-testing of the second pipe 14 and anypipe-to-pipe connectors 34 during deployment.

An exemplary method of adjusting the buoyancy of a pipe, such as thesecond pipe 14 described above, may comprise coupling a buoyancy controllayer to the pipe. FIG. 4 illustrates an exemplary composite tube 50having an interior liner 52, a composite layer 54 and a buoyancy controllayer 56. The composite tube 50 is generally formed along a longitudinalaxis and can have a variety of cross-sectional shapes, includingcircular, oval, rectangular, square, polygonal, and the like. Theillustrated tube 50 has a circular cross-section. The composite tube 50can generally be constructed in manner analogous to one or more of thecomposite tubes described in commonly owned U.S. patents and patentapplications: U.S. Pat. No. 6,016,845, U.S. Pat. No. 5,921,285, U.S.Pat. No. 6,148,866, U.S. Pat. No. 6,004,639, and U.S. Pat. No.6,286,558, U.S. patent application Ser. No. 10/134,071 filed Apr. 29,2002, U.S. patent application Ser. No. 10/134,660 filed Apr. 29, 2002,and U.S. patent application Ser. No. 10/288,600 filed Nov. 5, 2002. Eachof the aforementioned patents and patent applications is incorporatedherein by reference. Although the following description is in connectionwith a composite pipe, one skilled in the art will recognize that thebuoyancy control layer described herein may be used in connection withany type of pipe, including, for example, steel pipes.

The buoyancy control layer 56 may be a layer of material(s) having adensity selected to adjust the overall density of the pipe 50 to providea desired buoyancy to the pipe. The buoyancy control layer 56 may becoupled to the pipe by extruding a material having the desired densityonto the composite layer 54 or other layer of the pipe 50, by wrapping amaterial having the desired density onto the composite layer 54 or otherlayer of the pipe 50, or by other methods of coupling a layer ofmaterial to layer of the pipe. The buoyancy control layer 56 may becoupled to the pipe 50 during fabrication of the pipe orpost-fabrication. The buoyancy control layer 54 may be bonded orun-bonded to the pipe.

In certain embodiments, the buoyancy control layer 56 may be a layer oflow density material incorporated within the composite tube to providebuoyancy to at least a longitudinal segment of the composite tube 50. Anoptional pressure barrier layer as well as other additional layersincluding additional layers of low-density material and additionalcomposite layers, may be provided external to the layer of low-densitymaterial. Although the layer 56 is illustrated as being disposedexternal to the composite layer 54, the exemplary layer 56 of lowdensity material may be disposed at any point throughout thecross-section of the composite tube 50 including, for example, betweenthe inner liner 52 and the composite layer 54. The layer 56 of lowdensity material may extend along the entire length of the compositetube 50 or may be disposed along one or more discrete lengths of thecomposite tube 50. The layer 56 of low density material may allowselected longitudinal segments or the entire length of the compositetube to have approximately neutral or minimal negative buoyancy. Forpipe rehabilitation as described above, the buoyancy of the second pipe14 is preferably adjusted to less than a specific gravity of 1.5grams/cm³ in water.

In an exemplary embodiment, the low-density material for the layer 56 isselected to have a specific gravity of less than or equal to about 1.25grams/cm³ in water. Suitable low density materials may include, forexample, syntactic foams, foamed thermoset or thermoplastic materialssuch as epoxy, urethane, phenolic, vinylester, polypropylene,polyethylene, polyvinylchlorides, nylons, thermoplastic or thermosetmaterials filled with particles (such as glass, plastic, micro-spheres,ceramics), filled rubber or other elastic materials, or composites ofthese materials. In certain embodiments, the buoyancy control layer 54may be a thermoplastic foam jacket that may be extruded onto theexterior layer of the pipe 50.

The material of the buoyancy control layer 56 may also be selected toprovide increased wear resistance to the pipe 50 and to reduce thecoefficient of friction of the exterior of the pipe.

References

All publications and patents mentioned herein, including those itemslisted below, are hereby incorporated by reference in their entirety asif each individual publication or patent was specifically andindividually indicated to be incorporated by reference. In case ofconflict, the present application, including any definitions herein,will control.

Equivalents

While the systems, methods, and tubes disclosed herein have beenparticularly shown and described with references to exemplaryembodiments thereof, it will be understood by those skilled in the artthat various changes in form and details may be made therein withoutdeparting from the spirit and scope of the disclosure. Those skilled inthe art will recognize or be able to ascertain using no more thanroutine experimentation, many equivalents to the exemplary embodimentsdescribed specifically herein. Such equivalents are intended to beencompassed in the scope of the present disclosure, and such equivalentsare intended to be encompassed by the following claims.

1. A system for rehabilitating a pipeline comprising a first pipe, saidsystem comprising: a first device coupled to a first portion of a secondpipe, wherein said first device is configured to push a length of saidsecond pipe into a first access point of said first pipe; and a seconddevice coupled to a second portion of said second pipe, wherein saidsecond device is configured to pull said second pipe through a secondaccess point in said first pipe, said second access point spaced adistance from said first access point; and wherein said first pipe isflooded with a fluid; wherein said second pipe further comprises abuoyancy control layer formed of a material having a density selected toadjust the overall density of the second pipe to provide a desiredbuoyancy to the second pipe.
 2. The system of claim 1, wherein saidfirst device is an injector or a reel.
 3. The system of claim 2, whereinsaid second device is a capstan, winch, tractor or propulsion jet. 4.The system of claim 1, wherein said second device is a capstan, winch,tractor or a propulsion jet.
 5. The system of claim 4, wherein saidsecond device is a capstan.
 6. The system of claim 5, wherein saidcapstan is connected to said second pipe with a rope.
 7. The system ofclaim 4, wherein said first device is an injector or reel.
 8. The systemof claim 1, wherein said fluid is selected such that said second pipehas about neutral or minimal negative buoyancy in said fluid.
 9. Thesystem of claim 1, wherein said fluid is selected from a brine andwater-based drilling mud.
 10. The system of claim 1, wherein said fluidfurther comprises a friction reducing fluid.
 11. The system of claim 1,wherein said buoyancy control layer is coupled to an exterior of saidsecond pipe.
 12. The system of claim 11, wherein said buoyancy controllayer has a specific gravity in water of less than about 1.25 g/cm³. 13.The system of claim 1, wherein said buoyancy control layer is anextruded layer on the exterior of said second pipe.
 14. The system ofclaim 1, wherein said buoyancy control layer is deposited on theexterior of said second pipe.
 15. The system of claim 13, wherein saidbuoyancy control layer comprises a thermoplastic foam.
 16. The system ofclaim 1, wherein said buoyancy control layer reduces the coefficient offriction of the exterior of said second pipe.
 17. The system of claim16, wherein said buoyancy control layer comprises a thermoplastic foam.18. The system of claim 1, wherein a sensor is affixed to said secondpipe.
 19. A system for rehabilitating a pipeline comprising a firstpipe, said system comprising: a first device coupled to a first portionof a second pipe, wherein said first device is configured to push alength of said second pipe into a first access point of said first pipe;and a second device coupled to a second portion of said second pipe,wherein said second device is configured to pull said second pipethrough a second access point in said first pipe, said second accesspoint spaced a distance from said first access point; wherein said firstpipe comprises a fluid such that said second pipe has about neutral orminimal negative buoyancy in said fluid, said second pipe comprising abuoyancy control layer formed of a material having a density selected toadjust the overall density of the second pipe.